Building structures are often built on site in most parts of the world. The problems of site constructions are well documented in past journal articles. The major problems of many site building methods are their high amount of skilled labor requirements and complexity of the building structures. In cases where the building system is too foreign to the local market, system acceptance will be very low. There are certainly many different types of building systems available in the market that compete to reduce cost, provide speed construction, and provide a more energy-efficient envelope at the same time. However, no system can reduce cost sufficiently, increase construction speed, provide more energy-efficient envelope, and have more culturally acceptable features at the same time. The local market, particularly, in the developing countries is enormous because these developing countries are where the majority of the world population growth occurs in the last 35 years.
The precast building industry has been evolving slowly for the last few decades in developed countries including United States and Europe. The core concept of most precast systems is still based mainly on very heavy load-bearing wall components. Load-bearing wall panel is a panel designed to carry the load above the panel and does not rely on a column system to support the load. In contrast, the non-load bearing wall panel is designed to carry load above the panel. However, a typical load-bearing wall system inherently has limitations in application and practice in most developing markets. For example, a typical precast system requires a large amount of capital for heavy equipment to manufacture and handle its panel components, making it a very unattractive investment relative to traditional cast-in-place system which is more easily practiced and implemented without heavy machinery. As a result, traditional cast-in-place concrete system remains widely practiced everywhere, including both developed and developing countries for many generations.
An example of such a traditional cast-in-place concrete superstructure 10 is shown in FIG. 1A and FIG. 1B including widely practiced traditional concrete columns 11 and traditional concrete floor systems 12 for low rise and high rise structure. FIG. 1A shows a traditional cast-in-place concrete frame superstructure 10 including cast-in-place columns 11 and floor systems 12 for a single story or low rise structure. In contrast, FIG. 1B shows a traditional cast-in-place concrete frame superstructure 10 including cast-in-place columns 11 and floor systems 12 for multiple stories or high rise structure. In either embodiment, its cast-in-place concrete frame superstructure 10 is well understood and trusted for generations. The superstructure's columns 11 are designed to carry the structure's load. In designing and determining the load capacity of the structure, the traditional cast-in-place concrete frame superstructure 10 will be much easier to understand and be trusted by the local developing population than a load-bearing precast wall system.
Another major advantage of traditional cast-in-place concrete superstructure over traditional load-bearing precast wall systems without columns is its flexibility for future renovations. For example, partition walls can be easily knocked down or moved to accommodate new floor layout or usage of space as space usage changes in time. However, the traditional cast-in-place concrete system, as shown, for example, in FIGS. 1A-1B, also has its weaknesses. Its biggest weakness lies in the construction of walls and partitions between load-bearing columns 11. The traditional method uses hundreds or thousands of concrete blocks or clay bricks to build the walls. Inherent major problems include slow construction speed, inconsistent quality and lack of insulation. In most cases its energy and noise performance is far lower than precast insulated walls. In today's environment and in the future, where energy consumption continues to rise as living standards increase, walls with insulation in them will save energy. In normal construction steps, the cast-in-place superstructure 10 is constructed first and is then followed with the construction of envelope walls and all partition walls. In the last few decades, another type of non-precast system using a light gauge steel frame and a thin sheathing has become an attractive alternative; however, acceptance has been very slow as most people in the developing market still prefer traditional masonry walls and do not like the flimsiness of its covering and its durability when compared to the traditional masonry walls.
Given the fact that at least 80% of 7 billion world population is living in developing countries and living mostly in traditional concrete frame housing, any precast system that does not resemble what people have been used to for generations and can offer better performance over traditional system will have little chance of acceptance and adoption. In addition to being unfamiliar in the local engineering community and end users, the high level of initial capital investment required for precast systems will make them unviable as a solution. Other non-concrete or non-masonry solutions have the same problem in their adaption as well. When people buy something as significant as their home they will want to buy something they trust and that has better value. A new building solution is desperately needed that has to be cheaper, faster construction time, higher thermal efficient performance to save energy, and has more culturally acceptable features as well.
In any market and in any innovation, end users or consumers will always accept and buy a better mouse trap because of its greater perceived value. The old mouse trap in construction technology can be referred to as traditional reinforced concrete frame with cast-in-place columns, beams, and floor. Typical load-bearing precast system from developed countries will not be perceived by the mass population in developing countries as a better mouse trap because of its lack of resemblances. This explains why most evolved precast building systems of the developed countries have failed in developing markets. The mouse trap—a home—is the most significant purchase in a person's life. As a result, not too many people are willing to buy something that does not perceive as a better mouse trap than the one they grew up in.
In recognizing all factors stated above, there is a need for a better building solution, particularly, in developing countries where developers or general contractors often do not have the excess capital for heavy equipment for traditional load-bearing precast systems.